1. Field of the Invention
This invention relates to a linear guide plain bearing used in machine tools, industrial machines, conveyance apparatuses, robots, various measuring instruments and so on.
2. Prior Art
Such a bearing is classified into a linear guide plain bearing and a linear guide roller bearing. One conventional linear guide plain bearing is disclosed in JP-A-9-296824. This bearing comprises a guide rail, having longitudinal grooves formed on an outer surface thereof, and a slider, which has grooves (corresponding respectively to the grooves in the guide rail) formed on an inner surface thereof, and is mounted on the guide rail for sliding movement therealong. Each of sliding members, made of lubricant-containing rubber or synthetic resin, is interposed between the corresponding opposed grooves of the guide rail and the slider. In this linear guide plain bearing, a lubricant (such as grease, paraffin hydrocarbon oil, mineral oil, ether oil and ester oil), impregnated in each of the sliding members, gradually oozes out, and is automatically supplied to the groove of the guide rail.
Another conventional linear guide plain bearing is disclosed in JP-A-2001-3934. This bearing comprises a slider, which has tapering sliding surfaces formed on an inner side thereof, and is made of a tin-containing-aluminum alloy sliding material (which exhibits a good sliding performance in a non-lubricating condition), and a guide rail. Tapering sliding surfaces, corresponding respectively to the sliding surfaces of the slider, are formed respectively on opposite side surfaces of the guide rail, and a solid lubricant-containing resin coating, which exhibits a good sliding performance in a non-lubricating condition, is formed on each of the sliding surfaces of the guide rail so that the sliding surfaces of the slider can slidingly move respectively on these resin coatings. In this linear guide plain bearing, the number of the component parts is smaller as compared with conventional products, and the working is easier, and therefore the linear guide mechanism of the non-lubricating structure, achieving the compact, lightweight and inexpensive design, can be maintained for a long period of time.
Here, a study will be made with respect to the linear guide plain bearing disclosed in JP-A-9-296824. In this linear guide plain bearing, the sliding members, each provided between the corresponding opposed grooves, are essential, and there are needed thick end caps fixedly securing the sliding members to the front and rear ends of the slider. Therefore, this plain bearing has drawbacks that the structure is complicated and that the number of the component parts is increased. Further, the grooves for the mounting of the sliding members are provided at the guide rail and the slider, and more specifically the grooves are formed respectively at the opposite side portions of the guide rail, while the grooves are formed respectively at the opposite side portions of the slider opposed respectively to the grooves of the guide rail. The guide rail and the slider need to have their respective predetermined thicknesses since the grooves, sufficiently large to receive the respective sliding members, must be provided at the guide rail and the slider. As a result, this bearing has drawbacks that the working and the mounting of the members become complicated, and that the bearing itself is increased in size, weight and cost.
Next, a study will be made with respect to the linear guide plain bearing disclosed in JP-A-2001-3934. In this linear guide plain bearing, the tapering sliding surfaces of the slider slide or move respectively on the tapering solid lubricant-containing resin coatings of the guide rail, and therefore it is thought that the reduction of a sliding resistance, achieved by the surface-to-surface sliding contact between the corresponding sliding surfaces, is limited.